Automation Direct D2-DCM, Руководство пользователя

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Building the Cable
14
Data Communications Module, 2nd Edition, 2/03
Network Amplifiers — If you have more than 16 slave stations, you must use an
RS422 amplifier to maintain the signal levels. The best amplifiers are regenerative,
that is, they try to improve signal quality by reducing any noise signals that are
present. (They amplify the signal and not the noise if possible.) Some amplifiers are
not regenerative and amplify the noise as well as the signal. You can purchase
amplifiers from several sources. The Black Box catalog is one of many good places
to start; they sell direct. Call 1–800–555–1212 and ask the 800 directory assistance
operator for their phone number. You can also look for a amplifier supplier on the
internet. One web site to look at is www.idealsolution.com, or search for other RS422
amplifier web sites. The following diagram illustrates some instances where an
amplifier is necessary.
Slave Slave Slave Slave
Master
Station
Slave
RS422
Amp
1-16 Slave Stations
Slave Slave Slave Slave
RS422
Amp
1-16 Slave Stations
RS422
Amp
Master
Station
Slave Slave Slave Slave
RS422
Amp
RS422
Amp
Slave Slave Slave Slave
RS422
Amp
RS422
Amp
Serial Slave Connection
Parallel Slave Connection